In recent years, vigorous attempts have been made to apply magnetoresistive elements using the tunnel magnetoresistance effect to magnetic random access memories (MRAMs). The MRAMs including magnetoresistive elements have advantages such as nonvolatile data storage, write time and read time of 10 ns or shorter, and 1015 or more times of data rewriting.
The magnetoresistance change rate (MR ratio) of a magnetoresistive element, however, is about 600% at maximum at room temperature. Accordingly, the ratio of a high resistance value to a low resistance value in an MRAM is less than that in nonvolatile memories of other kinds. Due to this, an MRAM with magnetoresistive elements requires highly accurate sense amplifiers. This may cause a problem of an increase in periphery circuit area. There is also a problem in that disposing such sense amplifiers to several locations in a memory circuit would be difficult.